Alot of it depends if you have a case on the phone. Many of the good cases out there unfortunately play havoc on bothe the light sensitivity and proximity sensors. Its the price you pay to make sure nothing happens to the phone, unfortunately.
Sent from my Sprint Galaxy Note II on Tapatalk Pro.
im a huge fan of Lux auto brightness, has profiles for day night car and cinema and the night mode is synced with your locations sunset times. works with tasker plug ins also, works great for going full brightness on certain apps and auto when not.